Action: Increase water turbidity to reduce fish predation by birds
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A randomised trial in France found that little egret Egretta garzetta foraging efficiency was lower in turbid water than clear.
Birds are visual predators and rely on detecting prey within the water in order to hunt. By obscuring predators’ search images overall predation rates might decrease and reduce bird-human conflict in aquaculture operations.
Supporting evidence from individual studies
A randomised trial in southern France found that little egret Egretta garzetta foraging efficiency (capture rate) declined significantly in turbid water, under captive conditions (Cezilly 1992). A 3 x 6 m pool (water depth 10 cm) was used. Nine adult egrets either foraged alone or in threes. Three trials were undertaken using clear or turbid water, with three densities of prey i.e. mosquito fish Gambusia affinis (1, 2, and 4/m²). Treatment order was randomised and trials lasted 5 min. Turbid water was created by adding clay (Secchi disc lost from view at 10 cm depth).